Method and apparatus for gait measurement

Abstract

A method and apparatus for gait measurement in which a walking aid such as a walker, cane, or crutch is instrumented with load sensors to measure the loads in the aid as it is being used. The measured loads are used to analyze the user's gait to insure proper selection and sizing of a walking aid, stability of the user, and proper limb loading. In a preferred embodiment, strain gauges are mounted on the legs of a walker and connected through a signal processing interface to a computer for data analysis and display. The gauges are mounted, calibrated, and connected to the signal processing interface so as to permit measurement of the axial, bending, and torsional forces in each leg of the walker as it is being used. This data is then used for qualitative and quantitative assessment of the user's gait.

We claim: 
     
       1. A system for measuring the gait of a person using a walker comprising: a walker comprising a plurality of support legs and at least one handle,   at least one first load sensor mounted to at least one of said support legs,   said first load sensor positioned to sense at least one of the axial, bending, or torsional loads in at least one of said legs,   at least one second load sensor mounted to said at least one handle,   signal processing means in electrical connection with said load sensors,   power supply means electrically connected to said signal processing means for supplying power to said signal processing means,   data processing means connected to said signal processing means for controlling said signal processing means and processing the data from said load sensor, and   data display means connected to said signal processing means for displaying the data processed by said signal processing means.   
     
     
       2. The system of claim 1 wherein said first load sensor is a strain gauge. 
     
     
       3. The system of claim 1 wherein said signal processing means, said data processing means, said power supply means, and said data display means are mounted to said walker. 
     
     
       4. The system of claim 2 wherein: said walker comprises four legs,   each of said legs is instrumented with at least two axially mounted strain gauges for sensing the axial loads in said legs.   
     
     
       5. The system of claim 4 wherein: each of said legs is instrumented with at least two axially mounted strain gauges for sensing bending loads in said legs.   
     
     
       6. The system of claim 4 wherein: each of said legs is further instrumented with two strain gauges mounted adjacent to and at opposite 45° angles from one of said axially mounted strain gauges for sensing the torsional loads in said legs.   
     
     
       7. An instrumented walker system comprising: a walker having a plurality of support legs and at least one handle,   a plurality of load sensors mounted to each of said legs,   a signal processing interface electrically connected to said load sensors,   a power supply electrically connected to said interface,   a computer connected to said interface for controlling said signal processing interface and processing the data from said load sensors, said computer having a display for displaying said processed data,   wherein said signal processing interface, said power supply, and said computer are mounted on said walker.   
     
     
       8. The system of claim 7 wherein said plurality of strain gauges are positioned so as to sense the axial, front-to-rear bending, side-to-side bending, and torsional loads in each of said legs. 
     
     
       9. A method for making gait measurements on a person using a walker, the method comprising: mounting at least one first load sensor to said walker, said first load sensor positioned to sense at least one of the axial, bending, or torsional loads in said walker and capable of supplying an electrical output signal,   mounting at least one second load sensor to said at least one handle, said second load sensor capable of supplying an electrical output signal,   detecting the output signals from said load sensors,   transmitting said output signals to a signal processing means,   processing said signals for communication to a data processing means,   converting said processed signals to values representative of the load sensed by said load sensor, and   displaying said load values.   
     
     
       10. The method of claim 9 wherein said first load sensor is a strain gauge. 
     
     
       11. The system of claim 1 wherein said second load sensor is positioned to sense at least one of the axial, bending, or torsional loads in said handle. 
     
     
       12. The system of claim 8 further comprising an alarm for alerting the user that the walker is imbalanced. 
     
     
       13. The system of claim 8 further comprising an alarm for alerting the user that too much weight is being borne by a limb. 
     
     
       14. The system of claim 8 further comprising an alarm for alerting the user that additional weight should be borne on a designated limb. 
     
     
       15. The system of claim 12 wherein said alarm is an audible alarm. 
     
     
       16. The system of claim 13 wherein said alarm is an audible alarm. 
     
     
       17. The system of claim 14 wherein said alarm is an audible alarm. 
     
     
       18. An instrumented walker system comprising: a walker having a plurality of support legs and at least one handle,   at least six strain gauges mounted to each of said plurality of legs, said at least six strain gauges comprising three axially mounted strain gauges and a strain gauge rosette, said axial gauges and said rosette spaced 90° apart, wherein said rosette comprises an axial mounted strain gauge and two strain gauges mounted adjacent to and at opposite 45° angles from said axial strain gauge,   a signal processing interface electrically connected to said strain gauges, said interface comprising a Wheatstone bridge circuit for each strain gauge,   a power supply electrically connected to said interface,   a computer connected to said interface for controlling said signal processing interface and processing the data from said strain gauges, said computer having a display means for displaying said processed data.   
     
     
       19. The system of claim 18 wherein said strain gauges are positioned to sense the axial, front-to-rear bending, side-to-side bending, and torsional loads in each of said legs. 
     
     
       20. The system of claim 7 wherein said load sensors comprise strain gauges.